Add error message for error code 25 in btcpd

[richardvtbtcp]

Hi All!
It is possible, when sending a raw transaction, show not just
"error code: -25
error message:" <- empty string
if error is "ERROR: AcceptToMemoryPool: absurdly high fees"
Otherwise you can’t find it out without a log in debug mode, and this not only on the btcp node, in block explorer when broadcasts - the same error without a description